For Access DB Numbers, containing field SeqNums, which contains records 1,2,3,4,5,6,7,9,10,11,15...
Add an AutoNumber field to assign sequential index numbers to your records. Access will then assign sequential numbers to your records, as in:
ID SeqNums
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 9
9 10
10 11
11 15
Then run this query:
SELECT Numbers.ID, Numbers.SeqNums, [SeqNums]-[ID] AS Diff
FROM Numbers
WHERE ((([SeqNum]-[ID])<>0));
Your results will show only the records where SeqNum minus ID (the autonumber index) is not equal to zero, indicating your sequential numbers that are "off." Each time the value of Diff changes, then that will indicate another skip.
ID SeqNums Diff
1 1 0
2 2 0
3 3 0
4 4 0
5 5 0
6 6 0
7 7 0
8 9 1
9 10 1
10 11 1
11 15 4
It's not foolproof, but it's a start. I suggest trying this in a _copy_ of your database first,to be sure not to inadvertently doing harm...